An ancient human like civilization exists on a planet like our own but warmer, with more deserts and smaller oceans. Climate change is forcing the daytime temperature slowly upwards. What measures might such a civilization take to protect itself from the increasing heat and roughly what sort of temperature would be survivable long term?

I understand what ancient civilizations did historicaly, but I'm more interested in different approaches that might be used at higher temperatures.

They have access to fresh water in deep wells refreshed by an aquifer charged by rain fall in a distant and inaccessible area. They are also near to the sea. The crops they grow have a similar heat resistance to the most heat resistant plants that grow in our desert regions. They are trapped in their current location by oceans and mountains so they can’t escape.

Edit
Clarification concerning "ancient", "human like" and "civilization"
This ancient civilization has no high tech, the human like beings only differ in insignificant ways from real humans. The answer can be based on any ancient human civilization prior to 400AD, but in the absence of any compelling reason otherwise I suggest the ancient Egyptians would be suitable. But their motivations would be more directed towards surviving in a warming environment than pyramid building.

$\begingroup$Are you looking for something like farmer-Tuareg?$\endgroup$
– L.Dutch♦Oct 25 '17 at 13:06

$\begingroup$@L.Dutch possibly, what special inovations did they come up with?$\endgroup$
– SlartyOct 25 '17 at 14:58

$\begingroup$In order for this to be answerable, you really need to specify the tech level of the civilization. The phrase "ancient human like civilization" can be interpreted multiple ways. Is it a society that is ancient with extreme high-tech? A society that is like some (unspecified) ancient human civilization's tech level (if so, equivalent to which "ancient" human civilization (there's considerable variation))? Something else? Are these beings actually human? If not, there's no way to answer much about "what sort of temperature would be survivable long term".$\endgroup$
– MakyenOct 25 '17 at 19:19

$\begingroup$@Makyen I thought I had specified the tech level sufficiently by saying “ancient”, but clearly not. This ancient civilization has no high tech, the human like beings only differ in insignificant ways from real humans. The answer can be based on any ancient human civilization prior to 400AD, but in the absence of any compelling reason otherwise I suggest the ancient Egyptians would be suitable. But their motivations would be more directed to surviving in a warming environment rather than building pyramids.$\endgroup$
– SlartyOct 25 '17 at 19:45

6 Answers
6

Dig.
Fresno is pretty close to what you describe. This guy Forestiere bought land sight unseen thinking he would grow fruit and nut trees but on getting there realized it was worthless. So he dug. When he got low enough, he planted the trees.

The qanats are really excellent. They are ancient long distance underground waterways. Maybe when you state in OP that your people are getting water from distant rain and you are aware of the practices of ancient civilizations, you know about the qanats. A think I think is really neat about them is that in addition to watering your plants, if you build over a qanat it can cool your house; air in the qanat is cool and you can pull it up into your house with the updraft from tall chimney. From linked Wikipedia.

Saltwater canals.

Water can locally reduce temperatures. This is why fountains are in public squares in hot places. Your folks are near the sea. I propose that surface saltwater canals could run through the communal areas of their cities. This would cool things a lot and could be useful for transportation too. These could be connected to an estuary and so the water would flow back and forth according to the tides, or just be directly contiguous like Amsterdam, above. The moving water would absorb heat. One could have windpowered saltwater fountains as well for extra heat absorption. Having moving, nondrinkable water coming thru the city would also be good for sanitary reasons.

I cannot think of an example of a desert city with canals like this - if someone knows one please link it up or feel free to edit this answer and add a screenshot.

Much depends on how much fresh water they can harvest, either by wells or by desalinating sea water.

To keep reasonably cool in hot climate needs a lot of water, to drink, in the first place, but also to cool down other things (animals and plants) less heat resilient.

Human body can resist very high temperatures (up to 60°C and more, for shorter periods) with enough drinking water, but "useful" animal and plants have a narrower range.

Humans and animals can also resort to bury into caves (just 20m underground temperature is almost independent from outside heat), but that is not the case for plants needing light to thrive.

Being an "ancient" civilization it doesn't (supposedly) have access to means to pull cold water from some hundred meter undersea (close to 4°C), so they should resort to keep wet some large overhead cloth; evaporation can lower temperature under it more than 10°C, which may be enough... but will require a lot of water (using sea water is dangerous for salt accumulation which won't be healthy for plants).

Water cooled structures: a large water reservoir on the roof, covered from direct sunlight put open to evaporation, connected to pipes in the walls. Would require a lot of energy pumping, but also doubles as a gravity based running water supply.

$\begingroup$I have seen old structures that were basically smallish, block-shaped buildings with cisterns on top. Supposedly our ancestors here swathed the insides of these buildings in cloth similar to burlap, then allowed water to trickle from the cisterns into the buildings, soaking the cloth and thus cooling the building's interior. These structures were used as primitive cold rooms in a hot climate.$\endgroup$
– RissiepitOct 26 '17 at 6:22

Taking from David Eddings' Dagashi, they might keep talking to a minimum to preserve moisture, possibly developing a sign language.

Are there large animals in your desert? Some might find a way to make a boat if the bones are large enough to make a frame and cover that with skin. That would be one way to escape. (Or if some areas have just enough trees to make a Polynesian-style ship.)
If slavery exists, the wealthy would probably have human-powered fans akin to slave owners in the American antebellum South.

$\begingroup$Some excellent answers so far. I was wondering if desalination would have been possible on a large scale to extract from the sea, or how deep they might have been able to delve into the ground for other fresh sources of water$\endgroup$
– SlartyOct 25 '17 at 15:03

$\begingroup$Non-scientific reply from a non-scientist: I imagine desalination would require large-scale evaporation of salty water, and then harvesting the condensate in some fashion. If they had a large, (semi-)natural sea cave with a natural chimney, which they may have widened or narrowed in some way, that might be a start. Adding runnels leading to receptacles to the inside walls of the chimney would close the solution. A hot spring of some sort would be even better.$\endgroup$
– RissiepitOct 26 '17 at 6:28

Further to the answer above quoting the Forestiere Underground Gardens, caves have often been used this way throughout history. In some cases people used existing caves, but it was a natural step to engineer complete underground settlements, taking advantage of the thermal mass of the rock to moderate temperatures. The many cave systems in Cappadocia are a perfect example of this, where entire villages were built primarily underground.

Cappadocia only had the houses underground, of course. The Forestiere Underground Gardens adds an extra element to this by also moving agriculture at least partially into the underground domain as well.